GWT & Dagger 2

[Vasco Andrade Silva]

Hi all,

I've been trying Dagger 2 with GWT and have been fighting to get things working. Could someone help?

My pom:

<dependency>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger</artifactId>
 <version>2.0-SNAPSHOT</version>
</dependency>
<dependency>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger-compiler</artifactId>
 <version>2.0-SNAPSHOT</version>
 <optional>true</optional>
</dependency>


[...]


<plugin>
 <groupId>org.codehaus.mojo</groupId>
 <artifactId>gwt-maven-plugin</artifactId>
 <version>${gwtVersion}</version>
 <executions>
 <execution>
 <goals>
 <goal>compile</goal>
 <goal>test</goal>
 </goals>
 </execution>
 </executions>
 <configuration>
  <module>my.Module</module>
 <extraJvmArgs>-Xmx2048M -XX:MaxPermSize=128M</extraJvmArgs>
 <runTarget>index.html</runTarget>
 <warSourceDirectory>${project.build.directory}/${tmpTargetDirectory}</warSourceDirectory>
 <buildOutputDirectory>${project.build.directory}/${tmpTargetDirectory}/WEB-INF/classes/</buildOutputDirectory>
 <hostedWebapp>${project.build.directory}/${tmpTargetDirectory}</hostedWebapp>
 <webappDirectory>${project.build.directory}/${tmpTargetDirectory}</webappDirectory>
 <webXml>${project.build.directory}/${tmpTargetDirectory}/WEB-INF</webXml>
 <generateDirectory>src/main/java</generateDirectory>
 <bindAddress>0.0.0.0</bindAddress>
 <jsInteropMode>JS</jsInteropMode>
 <closureCompiler>true</closureCompiler>
 </configuration>
</plugin>

My issues are:

#1 generated sources aren't available for gwt compilation

running:

mvn compile

no errors are found in the compilation phase, dagger 2 generated sources land in target/generated-sources/annotations/

However running:

mvn compile gwt:compile

GWT compilation outputs the following error:

[ERROR] Errors in 'file:/path/to/project/src/main/java/path/to/project/client/ProjectEntryPoint.java'
[INFO] [ERROR] Line 79: No source code is available for type path.to.project.client.Dagger_ProjectComponent; did you forget to inherit a required module?
[INFO] [ERROR] Hint: Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly

the problem seems related with the fact that GWT compilation isn't including the generated sources, as target/generated-sources/annotations/ isn't included in the classpath of the GWT compiler. The project class paths that are included in GWT compile command are:

/path/to/project/target/tmp/WEB-INF/classes
/path/to/project/target/src/main/java

#2 Eclipse "doesn't follow" Dagger 2 generate sources (not related with GWT per-si)

I configured Eclipse (Luna edition) with m2e-apt plugin (http://marketplace.eclipse.org/content/m2e-apt). My project works as a maven project in Eclipse.

However when I change something in dagger (Component, Module, etc.) the generated sources aren't immediately generated, I need to do "Maven > Update Project".

#3 Eclipse imports errors on Dagger 2 generated files open (not related with GWT per-si)

When I open a file that was generated by dagger 2 (in target/generated/sources/annotations) eclipse doesn't know how to import other sources from target/generated/sources/annotations which lead to several compile time errors in those generated files. Additionally, from that point on Eclipse confuses himself and makes the project source files (in src/main/java) that are referring to generated dagger files (e.g. Dagger_ProjectComponent) to also be in error (eclipse doesn't know anymore to import those symbols).

To overcome this I have to do "Maven > Update Project". Note, however, that every time I open a dagger2 generated file, this happens again.

--

Has someone succeeded getting dagger 2 and GWT (and Eclipse) working together smoothly?

Also, any help to overcome the reported issues would be great (specially issue #1).

Thank you,

Vasco

[Vasco Andrade Silva]

Errata: 

"""

The project class paths that are included in GWT compile command are:

/path/to/project/target/tmp/WEB-INF/classes

/path/to/project/src/main/java

[Jens]

You need to add the generated sources as Eclipse source folder to make them usable in Eclipse, e.g.: http://stackoverflow.com/questions/7160006/m2e-and-having-maven-generated-source-folders-as-eclipse-source-folders

Maybe the above also fixes the gwt:compile class path issue.

For successful GWT compilation you also need Dagger + javax.inject sources and a GWT module to make them available to GWT compiler. I have done an initial pull request for Dagger to simplify that in the future: https://github.com/google/dagger/pull/119

-- J.

[Vasco Andrade Silva]

Jens thank you for your reply.

What's the best way to include your PR (https://github.com/google/dagger/pull/119) in a project?

[Jens]

What's the best way to include your PR (https://github.com/google/dagger/pull/119) in a project?

Its a branch in my dagger fork that you can simply build and install into your local repo: https://github.com/jnehlmeier/dagger/tree/gwt-integration 

-- J.

[Thomas Broyer]

On Tuesday, February 24, 2015 at 2:29:17 PM UTC+1, Vasco Andrade Silva wrote:

My issues are:

#1 generated sources aren't available for gwt compilation

running:

mvn compile

no errors are found in the compilation phase, dagger 2 generated sources land in target/generated-sources/annotations/

However running:

mvn compile gwt:compile

GWT compilation outputs the following error:

[ERROR] Errors in 'file:/path/to/project/src/main/java/path/to/project/client/ProjectEntryPoint.java'
[INFO] [ERROR] Line 79: No source code is available for type path.to.project.client.Dagger_ProjectComponent; did you forget to inherit a required module?
[INFO] [ERROR] Hint: Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly

the problem seems related with the fact that GWT compilation isn't including the generated sources, as target/generated-sources/annotations/ isn't included in the classpath of the GWT compiler. The project class paths that are included in GWT compile command are:

/path/to/project/target/tmp/WEB-INF/classes
/path/to/project/target/src/main/java

Which version of the maven-compiler-plugin are you using? m-compiler-p didn't add the generated-sources to the compileSourceRoots until version 3.2: https://jira.codehaus.org/browse/MCOMPILER-157, so you had to use the build-helper-maven-plugin to add it.

[Vasco Andrade Silva]

Thank you Thomas and Jens.

Thomas, I was using v. 2.3.2 for maven-compiler-plugin, upgraded to 3.2 and everything worked without build-helper-maven-plugin as you described - thanks!

Jens, I did as you said and everything worked! I Hope that the Dagger 2 team merge your PR asap - thank you!

I couldn't make Eclipse work as good as it should (still have issues #2 and #3) and I'm still relying on "Maven > Update Project" - I'll deep dive in https://www.eclipse.org/m2e/documentation/m2e-execution-not-covered.html and see if I can make any progress.

[Roger Küng]

Could you please be a little more precise? I didn't manage to install the fork, and since the pull request still hasn't been accepted it would be great if you could elaborate more on this.

[Jens]

Could you please be a little more precise? I didn't manage to install the fork, and since the pull request still hasn't been accepted it would be great if you could elaborate more on this.

Since my fork is already 6 month old and I haven't rebased my changes yet it is probably best if you just clone the google dagger repository. Once you have done that you can do

git fetch origin pull/119/head:gwt-integration

This should give you a new local branch named gwt-integration which contains the changes of my pull request. Now you can decide if you want to rebase that local branch on a release tag (e.g. dagger-2.0.1) or on the master branch. Finally you just build dagger using mvn package or mvn install.

-- J.

[alucard]

Are there any examples/tutorials on how to use Dagger2 with GWT. It would be very helpful. 

[Jens]

Are there any examples/tutorials on how to use Dagger2 with GWT. It would be very helpful. 

You need to inherit the Dagger GWT module and then you can use any Dagger 2 tutorial as there is no difference in usage with GWT.

-- J.